Cloud seeding generator



April 10, 1956 MaCCREADY, JR 2,741,601

CLOUD SEEDING GENERATOR Filed Sept. 4, 1951 RAD/O RECE/VE/P TUNED W/ TH F/L TER 7'/ME DELAY (/000 was)? TUNED F/L 75/? (2000 CR 5.)

2 Sheets-Sheet l PROPANE GAS IN VEN TOR. PAUL B. MACCREADY, JR.

A 7' TORNE V April 10, 1956 I p B. acc AD JR 2,741,601

CLOUD SEEDING GENERATOR 2 Sheets-Sheet 2 Filed Sept. 4, 1951 IN! 'EN'IOR. PAUL B. MACCREADY, JR

94C 8% NE E By 90% g A 7' TORNEV CLOUD SEEDING GENERATOR Paul a. MacCready, Jn', Pasadena, Calif. Appiication deptenlber 4, 1951, Serial No. 244,879

4 Claims. (CL-252-359) This invention relates to improved apparatus for controlling the operation of generators for producing cloud seeding nuclei.

Heretofore cloud seeding generators have been manually operated by an attendant located at the generator. When several cloud seeding generators are employed simultaneously or in a sequence, such an arrangement requires an operator for each generator and it is difficult to direct the operation of the generators from a central location. Also, such an arrangement does not readily permit the generators to be located in inaccessible places.

These dificulties are minimized in the cloud seeding generators of the present invention by providing compact cloud seeding generators which may be left unattended and which are controlled from a central station by means of radio signals. Any number of the cloud seeding generat-ors may be controlled simultaneously or in any desired sequence by a single operator at the central station.

in one embodiment of the invention, a cloud seeding generator is provided with radio receiving apparatus which is responsive to radio frequency signals which are modulated by two audio signals of dilferent frequencies, and which serves to activate the cloud seeding generator when one of the audio signals is received and to deactivate the cloud seeding generator when the other audio signal is received. Preferably the radio receiving apparatus is equipped with a time-delay circuit so that it will not respond to signals of short duration.

In another embodiment of the invention, timing apparatus is employed in conjunction with the radio receiver so as to energize the receiver only during predetermined portions of each hour. This embodiment of the invention may be employed to simplify the radio control apparatus since audio signals of only one frequency are required to control the activation and de-activation of the cloud seeding generator, and, if desired it may be employed to conserve the consumption of electrical power in the receiving apparatus.

The invention will be fully understood from the following description and the drawings in which:

Fig. l is a schematic diagram of one embodiment of the invention; and

Fig. 2 is another embodiment of the invention wherein the control apparatus includes a timing device.

In Fig. 1, the apparatus for producing the cloud seeding nuclei is a silver iodide generator which produces smoke by burning a sprayed acetone solution of silver iodide in a propane flame.

A flame holder 16 is employed to produce the cloud seeding smoke, and the propane gas and the silver iodide solution are applied to the flame holder through a nozzle 12 which may be a conventional paint sprayer nozzle, for example. A tank 14 serves to contain the propane gas, and a valve 16 serves to provide the apparatus with gas at a constant pressure. The output of the valve 16 is connected directly to a pilot light holder 18, and to the nozzle 12 through a valve 20 which serves to control the flow of the propane 'gasto the nozzle 12.

2,741,60l Patented Apr. 10, 1956 A tank 22 serves to contain the acetone solution of silver iodide, and the upper portion of the tank 22 is connected to the propane gas system through a T 24 so that the tank 22 is pressurized by the pressure of the propane gas. The acetone solution of silver iodide is supplied to the nozzle 12 through a filter 26, and a sump 28 is provided at the base of the tank 22 for further purifying the solution.

The nozzle 12 is provided with a control shaft 30 which serves to control the flow of the silver iodide solution through a needle valve into the nozzle 12. The valve 20 is provided with a toggle shaft 32 which serves to turn the propane gas on or off.

The operating sequence of the smoke generator is as follows: The propane gas is turned on by means of the toggle shaft 32 and the gas is ignited by the pilot 18, a needle-valve in the nozzle 12 is opened wide by means of the control shaft 30 so as to clean the nozzle and provide an even flow of the silver iodide solution, and then the needle valve is partially closed by means of the control shaft 3i) so that the needle valve is approximately one-half open.

When the smoke generator is turned off, the sequence of operation is as follows: The needle valve which controls the flow of the silver iodide solution is closed compietely by means of the shaft 30, and then the propane gas is turned oh by means of the toggle shaft 32.

These operations are accomplished by means of a motor 34 which drives a control arm 36 at a slow speed by means of a crank 38 which is connected by gears to the armature of the motor. For example, the motor 34 may cause the crank 38 to make one-half of a revolution per minute.

The control arm 36 is provided with a slot which straddles a fixed pin 39, so that the arm 35 is free to move back and forth and so that the end of the arm 36 which is connected to the crank 38 can move up and down.

Lugs 44 i2, 44 and 46, which are mounted on the control arm 3d, serve to actuate the toggle shaft 32 and the control shaft 30 of the needle valve in the nozzle at appropriate times so as to accomplish the sequence of operations described above. The lugs 44 and do serve to move the toggle shaft 32 and thereby turn the valve 20 on and off. The lugs 40 and 42 serve to contact the respective cams 48 and 50, which are rigidly attached to the shaft 3a? of the needle valve, and thereby serve to control the flow of the silver iodide solution into the nozzle 12.

A battery 52 is provided for energizing the motor 34, and a pair of switches, 54, 56, and a pair of relays, 58, 60 serve to turn the motor on and off at the desired times.

A crank 62, which is rigidly attached to the armature of the motor 3 and which carries a spring extension 64, serves to operate the switches 54 and 56. The switches 54 and 56 are normally closed, and the electrical circuit which connects the battery 52 to the motor 34 is arranged so that when both the relays 58 and 60 are d e-energized, the motor 34 is tie-energized whenever either of the switches 54 or 56 is open. When the switch 54 is open and the switch 56 is closed, the motor 34 is energized when the relay 5% is operated, and the motor continues to be energized until the switch 56 is opened. When the switch S6 is opened and the switch 54 is closed, the motor is energized when the relay 60 is operated and the motor continues to be energized until the switch 54 is opened.

The relays 58 and 60 are controlled by means of radio signals which are received by a receiver 66. The output of the receiver 66 is applied to a pair of tuned filters 68 and 70 which are tuned to pass different audio fretuency signals. For example the filter 68 may pass ignals having a frequency of 1,000 cycles per second, and he filter 70 may pass signals having a frequency of 1,000 cycles per second.

When a radio frequency signal is received which is modulated at the frequency of 1,000 cycles per second, he receiver 66 and the filter 68 cause the relay 5% to )perate, and when a radio frequency signal which is moduated at a frequency of 2,000 cycles per second is re- :eived, the receiver 66 and the filter 70 cause the relay S0 to operate.

Preferably, the radio receiver 66 is provided with a :iine-delay circuit of a .type which causes the receiver 56 to produce the audio frequency control signals only f the modulated radio frequency signals are received for 1 certain period of time. In this manner, the likelihood of the operation of the generator being interfered with by electromagnetic waves created by lightning or by interfering radio signals is minimized.

As shown in Fig. l, the generator for producing cloud seeding nuclei is turned off. In order to turn the generator on, an operator at a central station causes a radio transmitter located at the central station to produce a radio frequency signal which is modulated at 1,000 cycles per second. When this signal is received by the receiver 66 during an appreciable period of time, the relay 53 is caused to operate and thereby energize the motor 34 so that the crank 62 is moved in a clockwise direction. The operator should cause the transmitter to produce this radio frequency signal for a suflicient time to cause the extension 64 to move so that it is no longer in contact with the control button of the switch 54, and then the motor 34 will cause the crank 62 to rotate until it con-- tacts the control button for the switch 56 even though the transmitted signal is stopped, since the normally closed switches 54 and S6 serve to complete the circuit for energizing the motor 34 during this period.

As the cranks 62 and 38 are moved in a clockwise direction by the armature of the motor 34, the control arm 36 is caused to move to the right and the lug 44 serves to move the toggle shaft 32 to the on position, and then the lug 44 slips past the arm 32. Shortly thereafter the lug 40 contacts the cam and starts opening the needle valve in the nozzle 12 by moving the a timing apparatus is employed which serves to energize the radio receiver only during intervals of time between minute 30 and 31 and between minute 45 and minute 46 of each hour.

The control arm 36 serves to actuate the same type cloud seeding generator as disclosed in Fig. 1. Switches 80 and 82 serve the same functions as the switches 54 and 56 shown in Fig. 1. That is, these switches serve to deenergize the motor 34 when the extension 64 operates the control buttons on the respective switches.

The output of the radio receiver 66 is applied to a single tuned filter 68 which serves to provide a signal which operates the control relay 84 and starts and stops the operation of the cloud seeding generator.

A control relay 86 is provided for the receiver, and this relay serves to cause the receiver to be energized only when its armatures are operated. It is to be understood that the sources of potential for the radio receiver are included within the block 66 which represents the receiver, and that the armatures of the relay 86 serve to apply these potentials to the receiving apparatus when the armatures are operated.

A battery 87 serves to provide the electrical energy for energizing the relay 86.

A clock 88 serves to cause the receiver to be energized at the times described above. Preferably, the clock 80 is an electric type. The minute hand 90 of the clock serves to operate a normally open switch 92 during the interval of time between minutes 30'and 31 of each hour, and it also serves to operatethe normally open switch 94 during the interval of time between minutes 45 and 46 of each hour. The hour hand 96 of the clock serves ,to operatev the normally open switch 98 every twelve hours for about ten minutes during the intervals of time control shaft 30. When the crank 38 has moved about one-half of a revolution, the needle valve is completely open, and as the crank 38 continues to rotate the lug 42 contacts the cam 58 and begins closing the needle valve. After the crank 33 is moved about three-fourths of a revolution, the needle valve is about half on, and then the extension 64 on the crank 62 contacts the control button on the switch 56 and causes the switch to open, thereby stopping the motor 34 and causing the generating apparatus to remain turned on.

The generator may be maintained in this condition for any desired length of time. When the operator at the control station desires to turn the generator off, he causes the transmitter to produce a signal which is modulated at an audio frequency of 2,000 cycles per second so as to operate the relay long enough so that the motor 34 causes the extension 64 on the crank 62 to move beyond the control button on the switch 56. As the crank 33 is caused to move in a clockwise direction, the control arm 36 serves to close the needle valve by means of the rotation of the cam 58 by the lug 42. After the needle valve which controls the flow of the silver iodide solution is fully closed, the lug 46 contacts the toggle shaft 32 and causes the valve 20 to be turned off. When the extension 64 of the crank 62 contacts the control button on the switch 54 and causes the switch contacts to open, the motor 34 is tie-energized and the apparatus remains in this condition until another radio frequency signal which is modulated at 1,000 cycles per second is received.

In the embodiment of the invention shown in Fig. 2,

between 00:25 and 00:35 and between 12:25 and 12:35. A relay 100 is energized by a battery 102 each time that the switch 98 is closed.

The apparatus is arranged so that the minute hand 90 does not operate the switch 98 and so that the hour hand 96 does not operate the switches 92 and 94.

A reversible motor 104 is provided for resetting the clock every twelve hours, and the motor 104 serves to rotate an arm 106 which has a V-shaped portion in the end thereof. A spring 108 which is connected to the arm 106 serves to maintain the switch 92 in an operated condition during the clock resetting operation. A pair of batteries 110 and 112 are provided for energizing the motor 104, and a pair of normally closed switches 114 and 116 serve to control the limits within which the armature of the motor 104 may rotate. An arm 118, which is connected to the armature of the motor 104, serves to operate the switches 1 14 and 116.

When the cloud seeding generator is turned off as shown in Fig. 2, the armature of the switch 80 contacts the back contact of the switch. The only time during each hour that the receiver will be turned on is during the time interval between 45 and 46 minutes, since this is the only time during which the switches 80 and 94 are both operated so as tocomplete the circuit between the battery 87 and the winding of the relay 86. ceiver then receives a signal which is modulated at 1,000 cycles per second, the relay 84 operates and completes the circuit between the battery 52 and the motor 34 so that the cloud seeding generator is turned on. As soon as the extension 64 on the crank 62 permits the arma ture of the switch 80 to move to the front contact of the switch, the relay 86 is de-energized and the receiver If the re- 7 of the genera-tor in response to the signal received during the time interval between 45 and 46 minutes.

When the cloud seeding generator is on and the extension 64 of the crank 62 is in contact with the control button of the switch 82, the armature of the switch 82 con tacts the back con-tact of the switch 82 and the generator can be turned otf only if a signal is received by the receiver 66 which causes the relay 84 to operate during the interval of time between minute 30 and minute 31.

If the cloud seeding generator is already turned off, a signal received during the time interval between minute 30 and minute 31 will not affect the operating condition of the generator.

By having the clocks of different cloud seeding generators set to energize the receivers at difierent times of the hour, it is possible to select which generator is turned on or off by controlling the time during which the transmitters at the control station operate.

This method of selective control requires that the clock in a remotely controlled cloud seeding genera-tor be fairly accurately synchronized with the clock which the operator at the control station employs to determine when the various signals should be transmitted. The motor 104 and the arm 106 are controlled by the signals received by the receiver 66 every twelve hours during the time intervals between 00:30 and 00:31 and between 12:30 and 12:31, and the clock 88 may be synchronized with the clock at the transmitter station by means of such signals.

The receiver 66 is turned on by means of the relay 86 each time that the switch 92 is operated by the minute hand 90, i. e., during the intervals of time between minute 30 and minute 31 of every hour. If a signal which is modulated at 1,000 cycles per second is received by the receiver 66 during one of these time intervals while the relay 100 is operated by means of the hour hand 96 and the switch 98, the relay 84 is caused to operate and close a circuit so that the motor 104 is energized by the battery 110 until the arm 118 operates the normally closed switch 114. The motor 104 causes the arm 106 to rotate toward the clock 88 and force the minute hand 90 between the V-shaped end portion of the arm 106 into the 34 minute position. The spring 108 serves to maintain the switch 92 in an operated condition during the resetting operation. At minute 34 the transmitted signal is stopped and the relay 84 is de-energized, thereby causing the armature of the relay 84 to close the circuit between the battery 112 and the winding of the motor 104. This causes the motor 104 to rotate in the opposite direction until the normally closed switch 116 is opened. The motor 104 is deenergized when the switch 116 is operated and the arm 106 is maintained in a position out of the path of the minute hand 90 until the clock 88 is reset again. Thus, the minute hand of the clock 88 may be accurately set to the 34 minute position twice a day if desired.

It is to be understood that the minute and hour hands of the clock are interconnected by means of gears, but they are connected to the clock mechanism by a clutch. Thus, the clock may be set by moving the minute hand.

It will be apparent that the apparatus shown in Figs. 1 and 2 may be employed for controlling the production of various types of nuclei used for cloud seeding, and that it is not limited to the use of an acetone solution of silver iodide. Also, it will be apparent that various fuels may be employed to heat the chemical which serves to produce the nuclei.

Also, it will be apparent that various methods of igniting the gas may be employed. It is sometimes desirable to use a second pilot light which projects into the flame holder at a different angle from that of the pilot light shown in Fig. 1, so that if one pilot light blows out, it will be re-ignited by the other pilot light.

As an alternative safety precaution a glo-plug may be mounted on a bi-metallic strip which is located adjacent to the pilot light flame holder so that if the pilot light goes out the glo-plug will be caused to move toward the portion of the pilot which projects into the flame holder and contacts a connector which conducts current to the gloplug. The electrodes of a spark coil may be similarly set in front of the pilot light flame holder, and the spark coil switch operated by a bi-metallic strip.

If desired, the equipment may be arranged so that the pilot light provides sutficient heat to keep the batteries and the receiving apparatus at a high enough temperature for effective operation so that the apparatus may be employed during extremely cold weather.

I claim:

1. In a generator for producing cloud seeding nuclei wherein the nuclei are produced by the application of heat to a chemical, the combination comprising means for producing heat, means for conveying a chemical to the heat-producing means, a movable arm for controlling said means for producing heat and said means for conveying a chemical to the heat-producing means in a predetermined sequence, a motor connected to the movable arm for actuating it, a radio receiver, and means connected between the output circuit of the receiver and the motor and responsive to a predetermined signal at the output of the receiver for actuating the motor for a predetermined period of time and thereby controlling the application of heat to the chemical.

2. The apparatus of claim 1, wherein the receiver is connected to a switching device for energizing the receiver, and wherein the last-named means includes timing apparatus connected in the circuit of the switching device for causing the receiver to be periodically energized during predetermined intervals of time.

3. In a generator for producing cloud seeding nuclei, means for producing heat, means for conveying a chemical from which the nuclei are produced to the heatproducing means, an electric motor, a first crank connected to the shaft of the motor for controlling the heat-producing means and the chemical-conveying means, a source of potential, a pair of switches connected in series between the source of potential and the motor, a second crank connected to the shaft of the motor for operating the switches in sequence when the motor is energized, a radio receiver, means connected to the output of the receiver for energizing the motor when a predetermined signal is produced in the output circuit of the radio receiver, and timing means for energizing the radio receiver during predetermined intervals of time.

4. In a generator for producing cloud seeding nuclei, the combination of, means for producing heat, means for conveying a chemical from which the nuclei are produced to the heat producing means, an electric motor, a first crank connected to the shaft of the motor for controlling the heat producing means and the chemical conveying means, a source of potential, a pair of switches connected in series between the source of potential and the motor, a radio receiver means connected to the output of the receiver for energizing the motor when a predetermined signal is produced in the output circuit of the radio receiver, means connected to the shaft of the motor for operating one of the switches when the shaft of the motor is in a first predetermined angular position whereby the heat producing means is energized, and means connected to the shaft of the motor for operating the other of the pair of switches when the shaft of the motor is in a second predetermined angular position whereby the heat producing means is de-energized.

References Cited in the file of this patent UNITED STATES PATENTS 1,484,405 Oswald Feb. 19, 1924 2,397,539 Dent Apr. 2, 1946 2,413,067 Purington Dec. 24, 1946 2,462,343 Wohlgemuth Feb. 22, 1949 2,527,231 Vonnegut Oct. 24, 1950 2,665,940 MacCready Jan. 12, 1954 

3. IN A GENERATOR FOR PRODUCING CLOUD SEEDING NUCLEI, MEANS FOR PRODUCING HEAT, MEANS FOR CONVEYING A CHEMICAL FROM WHICH THE NUCLEI ARE PRODUCED TO THE HEATPRODUCING MEANS, AN ELECTRIC MOTOR, A FIRST CRANK CONNECTED TO THE SHAFT OF THE MOTOR FOR CONTROLLING THE HEAT-PRODUCING MEANS AND THE CHEMICAL-CONVEYING MEANS, A SOURCE OF POTENTIAL, A PAIR OF SWITCHES CONNECTED IN SERIES BETWEEN THE SOURCE OF POTENTIAL AND THE MOTOR, A SECOND CRANK CONNECTED TO THE SHAFT OF THE MOTOR FOR OPERATING THE SWITCHES IN SEQUENCE WHEN THE MOTOR IS ENERGIZED, A RADIO RECEIVER, MEANS CONNECTED TO THE OUTPUT OF THE RECEIVER FOR ENERGIZING THE MOTOR WHEN A PREDETERMINED SIGNAL IS PRODUCED IN THE OUTPUT CIRCUIT OF THE RADIO RECEIVER, AND TIMING MEANS FOR ENERGIZING THE RADIO RECEIVER DURING PREDETERMINED INTERVALS OF TIME. 